1. Field of the Invention
The present invention relates to a touch measurement system for measuring a workpiece and including a touch probe for detecting touching of the workpiece by a touch probe stylus and having at least one sender for emitting an infra-red light in response to detection of the touching, and a receiving unit including a housing having a window permeable to an infra-red light, an infra-red light receiver located in the housing interior for receiving the infra-red light emitted by the sender of the touch probe, and a unit likewise located in the housing interior for processing the infra-red light received by the receiver.
2. Description of the Prior Art
Touch measurement systems of the type described above are used for determination of a relative position or surface coordinates of a workpiece or a tool of a machine tool or of a coordinate-measuring machine upon touching. On the touch probe, at least one sender for emitting infra-red light in response to the touching is arranged. The infra-red light, which is emitted by the sender, is transmitted to a spaced from the touch probe, receiving unit that converts the received infra-red light into a trigger signal and transmits the trigger signal to the motion control that controls the displacement of the touch probe.
A touch measurement system of the type discussed above is disclosed in German Patent DE-34 22 180 C2. The receiving unit has a housing the opening of which is closed by a window permeable to infra-red light. In the window, there is arranged an infra-red filter for screening or eliminating visible light.
The touch measurement systems of the type described above should meet higher and higher requirements to their reliability. On one hand, the touch measurement systems should be able to function with the distance between the touch probe and the receiving unit increasing more and more and, on the other hand, the touch measurement systems become subjected to ever increasing influence of interference-creating devices, e.g., powerful motors.
Accordingly, an object of the present invention is to provide a touch measurement system with an increased functional reliability.